Primary immune deficiencies (PIDs) are a group of rare disorders of the immune system that result in increased susceptibility to infections, autoimmunity and malignancies. The most severe forms of PIDs are fatal, unless immune reconstitution is achieved by hematopoietic cell transplantation (HCT), enzyme replacement or gene therapy; other PIDs may be treated with biologics or immune modulation. Because of the many disease- and treatment-related variables that may affect outcome after HCT, careful collection of data in Registries and multicenter collaborations are needed to facilitate analysis of outcome and develop prospective clinical trials. In 2009, the Primary Immune Deficiency Treatment Consortium (PIDTC) was established to carry-out retrospective, cross-sectional and prospective studies to define risk factors, long term outcomes and late effects in children with Severe Combined Immunodeficiency (SCID), Wiskott-Aldrich Syndrome (WAS), Chronic Granulomatous Disease (CGD) and auto-inflammatory diseases who receive HCT or other forms of definitive treatment. The first PIDCT Scientific Workshop was held in San Francisco (2011), followed by annual Workshops in different host cities. These workshops and Education Days provide a unique and critical forum to assemble experienced and young investigators from all major centers in North America involved in the treatment of these disorders, as well as biostatisticians and Patient Advocacy Groups and have been responsible for initiating the development of national and international collaborations. The proposed 10th PIDTC Scientific Workshop and Education Day at the Asilomar Conference Grounds, in Pacific Grove, CA (PIDTC2020) will focus on new timely topics to further advance the development of clinical trials aimed at improving treatment of PIDs, the cause and treatments of Primary Immune Regulatory Disorders (PIRDs), gene therapy, and our active collaborations with Patient Advocacy Groups. The specific objectives are: 1) To disseminate information on survival, clinical status, and immune function in patients with severe PIDs who have received HCT or other forms of treatment 2) To initiate data collection and analysis in other forms of severe PIDs that can be treated by HCT 3) To have an emphasis on PIRD pathogenesis, diagnostic, and treatments. 4) To analyze relevance of biological markers that predict successful immune reconstitution following HCT 5) To discuss the results of novel approaches to HCT for PID and PIRD that may minimize transplant- related toxicity while allowing robust and durable engraftment and immune reconstitution 6) To prompt development of clinical trials in the field of HCT for PIDs 7) To promote education of young investigators with a specific interest in treatment of PIDs 8) To actively recruit and train under-represented minority physicians to the field of PID 9) To increase synergy among Patient Advocacy Groups actively involved in PID awareness campaigns